Bacteria including carboxydotrophic acetogens Clostridium autoethanogenum or C. ljungdahlii produce fatty acids in biosynthesis of lipids and cell membranes.
In wild-type Clostridia strains, flux down the fatty-acid pathway is significant with lipids accounting typically for 5-6% (w/w) of the dry cell mass (respectively 1-1.5 (w/w) % of the wet cell mass) (Lepage et al., 1987, Microbiology 133: 103-110). Typically more than 95% of the lipids are in very defined C16-C18 chain length range (Lepage et al., 1987, Microbiology 133: 103-110), with 12:0, 14:0, 14:1, 16:0, 16:1, 17Δ, 18:0, 18:1, 194 fatty acids present.
Fatty acids (FAs) and their derivatives are energy dense and therefore have potential as biofuels for use as a “drop-in” transportation/jet fuel and/or for the production of other industrial chemical compounds. Examples of fatty acid derivatives include biodiesel, free fatty acids, alkenes and alkanes.
Biodiesel is a mono-alkyl ester and can be used alone in standard diesel engines, or can be blended with petrodiesel. It can also be used as a low carbon alternative to heating oil. In 2009, worldwide more than 3.5 billion gallons of biodiesel were used. Biodiesel is normally derived chemically from vegetable or animal fat by transesterification of lipids in the presence of alcohol to yield glycerine and a mono-alkyl ester. Biodiesel produced by this process can however lead to damage of diesel engines due to variations in the oils from various animal and vegtebale sources which are not very defined with a wide range of carbon chain length (Fukuda et al., 2001, Biosci Bioeng 92: 405-416). Critical points are dilution of motor oil, coking of piston rings, corrosion of hydraulic components, and depositions in the injection system, resulting from the production process and fuel aging, resulting in some automotive manufacturers to refuse the use of animal or vegetable derived biodiesel in some of their models (Kopke et al., 2011, The Past, Present, and Future of Biofuels—Biobutanol as Promising Alternative, In: dos Santos Bernades (Ed.) Biofuel Production-Recent Developments and Prospects, InTech, 451-486).
The current generation of biofuels that use either food or non-food crops to produce sugar or cellulose-based feedstocks may have drawbacks relating to land-use, food-security, volatility of supply and environmental issues.
It is an object of the invention to overcome these issues and provide a method of production of biodiesel, or at least to provide the public with a useful choice.